Distance-Time Graphs
What does a horizontal line on a distance-time graph mean?
At rest
What is the formula for calculating speed?
Speed=Distance/time
What are balanced forces?
Forces that cancel each other out and have a net force of zero.
What is inertia?
An object's tendency to resist a change in its motion.
What two measurements do you need to calculate speed?
Distance and time
What does a steeper line on a distance-time graph mean?
Object is speeding up.
A student runs 100 meters in 20 seconds. What is the student's average speed?
5 m/s
What happens to an object's motion when balanced forces act on it?
No change in motion
Which of Newton's laws states that an object at rest stays at rest unless acted on by an unbalanced force?
1st Law
A car travels 180 miles in 3 hours. What is its average speed?
60 mph
A distance-time graph shows an object staying at 20 meters from 5 seconds to 15 seconds. How long was the object stopped?
10 seconds
What is the main difference between speed and velocity?
Velocity includes direction, while speed does not.
A box is pushed to the right with 20 N of force and to the left with 12 N of force. What is the net force and direction?
8 N to the right
Why does a passenger's body move forward when a car suddenly stops?
Because of inertia. The passenger's body tends to continue moving forward.
An object has a net force of zero. Does that mean the object must be stopped? Explain.
No. The object could be at rest or moving at a constant velocity.
How can you tell when an object is moving away from its starting point on a distance-time graph?
The distance is increasing, the line is going up.
A car travels 240 miles in 4 hours. What is its average speed?
60 mph
Two students pull on opposite ends of a rope with 30 N of force each. Are the forces balanced or unbalanced?
Balanced
A ball rolls across a perfectly frictionless surface. What will happen when the person stops pushing it?
The ball will continue moving at a constant speed in a straight line because there is no unbalanced force acting on it.
A family travels 90 miles, stops for lunch, and then travels another 150 miles. The entire trip takes 6 hours, including the stop. What is their average speed
40 mph
An object travels 60 meters in 20 seconds, stops for 10 seconds, and then returns to its starting point. Draw what the distance-time graph would look like.
The line slopes upward, becomes horizontal for 10 seconds, and then slopes downward toward zero.
Two trains travel east for 150 miles. Train A takes 3 hours, while Train B takes 5 hours. What do the trains have in common?
Both travel the same distance and direction.
A ball experiences 15 N of force to the east and 22 N of force to the west. What is the net force, and how will the ball's motion change?
7 N west. The ball will accelerate toward the west.
Why is it harder to change the motion of a bowling ball than a tennis ball?
The bowling ball has more mass, which means it has more inertia.
A student walks 40 meters east in 10 seconds. What is the student's average speed and average velocity?
Average speed = 4 m/s. Average velocity = 4 m/s east.